Wrong. Tobirama created Edo tensei in a time of war, if Madara seen Edo tensei used plenty of times to know it's seal then of course Hashirama was alive, he even made comments about it when Orochimaru summoned them right here
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. Also Tobirama won't sacrifice Senjus, he would to their enemies that they captured and in a time of war you're not going to be nice to your enemies so Uchihas and other clans were more likely used.
Also Tobirama, unlike Danzo, wouldn't sacrifice his comrades. He put his team before himself and let them live even thought he was Hokage
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and
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. Tobirama was hard on the Uchihas because he knew them so well and knew how well they can lose control
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and
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.
Also you seem to forget that Tobirama told Hashirama that he can't just make Madara Hokage because he's forgetting about the people and to listen to what they want before making decisions that effect them
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. Tobirama also is the one who created the Chunin exam which Hiruzen explained was made to not only evaluate the genin's strength but also the village's which prevent wars
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,
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,
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. He created the Academy system and created the Anbu black opts. That's something Shikamaru would do as a genius.